In the field of pressure-reducing devices or the like, particularly for high pressures, axially slidable valves are used which are constructed in the form of a metallic member which is turned to form a stem having an enlarged head provided with a recessed seat for fixedly embedding therein a special material insert designed to establish a tight seal against an outlet nozzle. It has been noted that practically this solution has a high manufacturing cost, since the application of said rubber insert by molding requires a previous sanding and pickling treatment and the application of a special primer glue to ensure a reliable fastening capable of withstanding high possible operation due to pressure seepage and action, and a comparatively long molding period as required to vulcanize rubber. The use of rubber, due to the particular molding requirements thereof, entails a further drawback because, upon molding said rubber insert, the axial bore in the stem, needed to create a pressure balance is liable to be obstructed; therefore, said hole shall be made in a final, expensive separate operation.
Since these articles shall be manufactured on mass-production, the existing solutions have shown to be too complicated and expensive, and this fact has urged the development of changes intended to ensure the utmost manufacturing economy and an improved functionality of the article, particularly in case of high pressures.